Periodically, societies come to a point where a lot of people, unprompted by anything other than their own consciences, simultaneously stand up, look around, and quietly say ‘Something is not quite right here.’ All being well, they hear each others’ words and find the courage to speak louder, and louder still, until something is done about it. They may have to fight to have it happen, but happen it does.

Many great changes have been effected this way. The slave trade ended. (At least in its incarnation as it was at the time. Modern slavery is still an issue, but at least it is no longer viewed as morally defensible.) Women gained the right to vote, the right to own property, and a whole heap of other rights besides. (Again, there’s still work to do. I cannot describe how lucky I feel to be a woman in Britain, where the NHS provides me with free no-questions-asked access to family planning services. Millions of other women still do not have the rights over their own bodies that I have over mine; many are even having those rights eroded by right-wing religious groups.)

And it’s happening again. All over the place, people are standing up and saying ‘There is something wrong in our society.’ The subject now is sexuality; equality and acceptance for those who define themselves in any other terms than heterosexual. This week in the UK the Same Sex Couples Marriage bill passed through the House of Commons. It only has to get through the House of Lords to be enshrined in law, and with a breathtakingly large Commons majority of 400 to 175 I believe that the Lords would be insane to block it.

The bill was brought to the House by the Conservative party, and one of the objections brought against it was that it had not been in their manifesto in the 2010 election, therefore they had no mandate to address it as an issue. This is a mark of how quickly marriage equality has come to the forefront of our concerns as a society. It was not in the Conservative party’s manifesto in 2010 because it had not occurred to anyone then that it was so important. In less than three years it has leapt to the forefront of Things That Must Be Sorted Out, and that is a result, not of government wonks sitting down in a room and deciding it is important, but ordinary people standing up and saying ‘Hold on a sec. We want this looked at.’

Why do I bring this up now? Because as a society we are already having this discussion about sexuality and I believe we must go further. We cannot just sort the sexuality issue out and then drop it. We must expand it to address the way society looks at gender as a whole.

The chances are that you view yourself as either male or female. Which it is will influence a whole lot of other things that you believe about yourself. Depending which it is, you will be possessed of a certain set of primary and secondary sexual characteristics. You may believe that you are good at certain things and bad at others. You may believe that you are more suited to certain careers; that you interact with other people in certain ways; that your behaviour in one situation is this, but in another situation is that. All because you are a woman, or because you are a man.

Yet is that really the case? Studies are beginning to show that stereotypical gendered behaviour is a self-fulfilling prophecy – men and women behave in certain ways precisely because they are told from birth that this is how they behave. Evidence is growing that expectation even affects what we are good and bad at. It is very possible that I am appalling at parallel parking precisely because the stereotype has been pushed on me all my life that women are bad at parallel parking. I am a woman, therefore I am told that parallel parking cannot be within my skillset, therefore lo and behold it is not.

Think around the people you know. Do they really divide up as neatly as many in society would have you think? In every woman that you know, are there not at least a handful of ‘masculine’ characteristics or skills? Doesn’t every man that you know quietly enjoy some things that are supposed to be the preserve of women?

The fact of gender being far more complex than an either/or choice extends beyond skills and character, into secondary sexual characteristics. Here’s one for you – I can grow a better moustache than some men I know. Fact. And even at my diminutive height (5’1, if you’re interested, or 155cm if you prefer) I have met men who, without specific genetic issues such as dwarfism, are shorter than me. Plenty of other women can look down on an average-height man. There are male altos and female tenors just as there are male homemakers and female engineers.

Some people are born with primary sexual characteristics on a scale between male and female. Many different presentations are recognised, covering the whole scope of possibility for ambiguous genitalia, variations in fertility, and complications in chromosomal arrangement. In many countries, these children are surgically re-assigned to one gender or another well before they themselves are able to understand the implications. These surgeries often result in loss of both fertility and sexual sensation.

Why do these surgeries occur, then? Because there is a stigma in our society against being anything other than clearly male or clearly female. The fact that intersex children are often surgically assigned to a gender before they can even walk only contributes to this stigma. Yet these surgeries have been declared completely unacceptable by the UN under its remit to eliminate torture.

This is why we need to extend society’s discussion on sexuality to include gender. Just as with sexuality, gender is not an either/or choice. It is not even a sliding scale, as that is still far too simplistic. We need to stop talking about men and women, gay and straight, and start talking about people and people, in all their infinite variety. To be born human is to enter a vast and beautiful world of possibility, and by pretending otherwise we are only harming ourselves and everybody we love.